Library System Project in C language
**Description:**
It is required to write a program that will maintain a library system. The system manages books information, library visitors, borrowing, ... etc. The system stores for each book the title, author, publisher, ISBN, date of publication, number of copies, current available number of copies, and category. In a library, a member may borrow many books at the same time. However, he must return the books before their due date. A member has a name (last and first), ID, address (building, street and city), phone number, age, and email address. You should maintain a structure that links a user with the book he borrowed, you should store book ISBN, user ID, date borrowed, data due to return, and date returned. You should have 3 separated files, one for books, another for users, and the last one for borrowing. It is better to read the files at the start of the program only, and you should save the changes only when the user selects save from the menu.